Train Question: FCO to Termini

Yes they increase in price. Which city are you going to from Rome.? I have bought cheap tickets once Rome to Naples and ended up missing the train but the low price was worth the risk.
And I just got back from Italy and all the trains I took especially Trenitalia were late by 10 to 70 minutes 100% of the time I was there. On fast trains with seat reservation I prefer Italo over Trenitalia.

Bari, to pick up a car and head into Puglia and Basilicata. Had originally planned to catch an Alitalia flight from FCO to Bari, but the choices have thinned.

What you are proposing is within reason. You can't count on it, but my experience is that trans-Atlantic flights from the US tend to arrive early by up to a half hour. Figure an hour for the train in (about 1/2 hour trip, up to another half hour waiting for the next train to leave); so that leaves you just under two hours to get through immigration, get bags, get to the train station at FCO, then from the express train to your Italo train. All of this is a very tight schedule, but with an early arrival and good timing catching the express, it can be done, or at least I have made it in to town in two hours.

Since you are willing to risk it, go ahead and try. I suppose you could just book later, have a lunch at Termini and relax, but it might be nice to get where you are going. You could also skip the train and pay a bit more for a taxi to termini, that might shave some time, the taxis are quicker to get to and less chance of a wait, just make sure to use the official City of Rome taxis, fixed rate into town, and for two people, not terribly more than the express train.

Thanks, Paul. I've never taken the train into Rome, primarily for jet-lagged brain reasons, but I thought it might be faster than negotiating mid-morning traffic in a taxi. Since most of my traveling snafus over the years have involved some form of public transport, I'm very happy to catch a taxi, or maybe even book a driver to Termini. Mostly want to get there and then on my way, since I can't relate the words "relaxation" and "Termini" in one sentence. Appreciate your help!

Do Trenitalia tickets increase in price if bought at the last minute?

Purchasing train tickets on the day of travel you pay the BASE fare on Trenitalia and the Flexi fare on Italotreno. You won't pay more and you can see it now on both official sites, walk-up fares are always displayed in advance to avoid surprises.

Trenitalia's high speed trains are better than Italotreno's, but since you are not travelling on an high speed line (at least for 10 years) you can forget it and take Italo.

thought it might be faster than negotiating mid-morning traffic in a taxi.

Cabs stop in front of the train station, trains arrive and depart from the tracks area. If Termini makes you nervous, you could appreciate the idea of not having to walk from the main entrance to the platforms through the shopping area. On the other hand, Italotreno #9919 is scheduled to depart from track 1 whereas the LE trains always arrive at track 24 in the morning. It's a 15 minutes walk, counting the time needed to stop in front of a Departures monitor and check the actual departure track of the train to Bari.

PS Maybe u already know it, but... I hope you are not leaving any luggage in a rental car while driving around Puglia.

Quite nice food and drink at the Mercato Centrale inside the Termini station and you can keep your bags with you --- makes it easy to wait for a train! Nothing like what is available in American train stations.

Thanks, everyone, for all your replies. It will be so good to be back in Italia in October!